Hydraulic brake booster



1386- 1 G. R. ELLIOTT HYDRAULIC BRAKE BOOSTER Filed May 14, 1945INVENTOR. 4 3000: ELL/arrnypnnnmc'nmnnoos'rnn: y -Gordon Re -Elliott,Ferndale,.Mi ch.,jassignor' to 3 f, .IrvingA. Puchner and Edward U.Demmer,'Mil-- 'waukee, Wis.

'i "Application May 14, 1945, Serial No. 593,723

8 Claims. lotto-54.5)

. 'l his'invention relates "to apower booster brake mechanismv employedin conjunction with a vehicle wheel brakingsystem, more particularly thebooster mechanism is adapted to O erate inconjunction with a, manuallyoperable master cylinder' and-a hydraulic'brake operating cylinder foreflectin'g vehicle power braking-assho'wn similarly in co-pendingapplication Serial Number 573 997, flledJa-nu ry 22, 1945.1"

. It is the object of -this invention to provide in j combination ahydraulic brake cylinder, an opcrating piston therein, and air-andvacuum control valve, and a valve control piston therefor, alsoprovisioned within said cylinder.

'It is the further-object herein to provide combination with a hydraulicbrake cylinder'an operating-piston thereim'a-power chamber, anintermediate a'i'rand vacuumvalve; a valve control piston also in saidcylinder; andmovable op-' erative means insaid powe'rch'amber,provisioned through said valve and its-control piston, and

joined to said'brake operating piston.

Other objects will be evidenced from the follow- Iingidetailedspeciflcation and drawing in which:

" Fig. 1 is'a side elevational'sectionof the .power brake boosterincluding a diagrammatic indication of the master cylinder,- a vehicleintake mani- ':fold, the wheel brake; cylinders; and the connectingconduits therefon;

Fig. 215 a fragmentary front elevational view) of the power chambershells clamping and aligning ring.

1 with the various elements positioned after brake application; I I

It will be understood that the above drawing illustrates merely apreferable embodiment of the invention, and that other embodiments arecon- .templated within the scope of the claims hereafter set out.- v I 1In the drawing, Fig. i, the vehicle brake wheel cylinders II are joinedby conduit l2 to outlet port IS in the end of hydraulic cylinder l4.Master cylinder I5 with manually operable foot pedal actuated means Itis joined to fluid intake port H of cylinder I4 by conduit l8.-

'The power' chamber consisting of hollow circular opposing shell'membersl9 and 20 isjoined to the left end of hydraulic cylinder I4 with theinterposed. 0n the it other hand,'air filter, 2i is 1 joined to thevalve; air intake port 28 baconduit 29'.

- Valve body 22 is secured to member'29, forming an integral part ofcylinder 14, by a plurality of circularly arranged studs 3fl,'two.ofwhich are shown in the drawing. The complementary valve body 2| islikewise secured to valve body 22 by a plurality of similar circularlyarranged bolts, not

shown in the drawing, with the central end portion of shell beinginterposed therebetween to provide a valve movable within cylinder l4being secured to one end of the hollowpowerrod v by the two pins 36retained by coil spring 31. Hollow valve con-1 trol piston 38 withsealing cup 39 is slidably provisioned within cylinder l4 in spacedrelation to fluid control piston 33. g

. Power rod 35 slidably supported through valve piston 38 is alsoslidably journaled through the elongated hollow-portion 40' forming apart of valvebody 2l, witha suitable seal M being pro-.

Figure 3-is an'enlarged fragmentaryelevational section of thehydrauliecylinder shown in Figure visioned within the end of member 40between member 40 and said rod.

Concave annular flexible diaphragm 42 with outer annular sealing rib 43,reinforced by hollow annular plate 44 issecured centrally to the leftend of hollow-power rod 35 by threaded nuts 45 on opposite sidesthereof. Circular spring retainer plate 46 registers with reinforcingplate 44, with coil spring" being interposed between plate 46 and valvebody 2|, to normally and resiliently retain diaphragm 42 in theinoperative position shown.

The opposing shell members l9 and 20 are respectively annularly flangedat 48 and 49 for encompassing the edges of annular rib 43 which forms apart of diaphragm 42. Annular concave broken clamp ring 50 is positionedover shaped flanges 48- and 49 the edges of said flanges resting in thebent portions 5| and 52 respectively of clamping ringv 50.

As shown in Fig. 2, brackets 53 and 54 are riveted on opposite sides ofclampin'g ring, and bolt 55 extends through corresponding openings insaid brackets, which are adjustably brought together by nut 56 fortightening clamping ring alr seat plate 3| with; air inlet openings 32.a a I I Fluid control piston 33 with sealing cup 34 is Pin I6 alsoadjustably retains flanged sleeve locking stop as well as a means ofaccurately aligning the two shells. Thus the correct amount of pressureto exert on the clamp ring to obtain a proper seal, a positive lock, anda proper alignment is predetermined.

Referring again to Fig. 1, coiled spring is provisioned within valvebody 3i22 with its left end engaging the valve housing and with its 1other endregisterlng withvalve control piston 38 to normally resistmovement thereof to maintain, when inoperative, vacuum communicationbetween vacuum chamber 58 and chamber 58. Vacuum communication isestablished with chamber 58 in shell l8 by means of openings 6! inhollow rod 35.

Vacuum is constantly maintained in chamber 32 within shell member 28 bymeans of passage 33 in valve body 2 l-22 which is joined by vacuumconduit 25. With vacuum communication established in both chambers 60and 62 it is seen that there is an equilibrium of pressure on oppositesides of diaphragm 42. By the existence of spring 41 it is thus seenthat when inoperative, the diaphragm and the power shaft assume theposition shown in Fig. l.

To obtain power braking, valve piston 38 is projected to the left onapplication of master cylinder i5. Piston 38 engages diaphragm plate 64carried by flexible diaphragm 65 peripherally retained between valvebodymembers 2| and 22. A secondary diaphragm plate 66 of reduced diameter issecured on the opposite side of diaphragm 65 by rivet 61 which extendsthrough both plates and said diaphragm.

Rivets 61 extend outwardly through air openings 32 in air valve seat 3|and are secured at their ends to air valve disc 68, which is normallyseated relative to air valve seat 3i by coiled spring 63.

Piston 38 when moved to the left contacts diaphragm plates 63 and 66closing oil vacuum communication between vacuum chamber 58 and chamber53. Further movement to the left of piston 38 efiects translation to theleft of diaphragm and corresponding unseating movement of air. valvedisc68 permitting air in chamber I8 to pass through annular opening 32 invalve seat 3|, and into chamber 58 which is in communication at alltimes with power chamber 50.

With air in chamber 68 and vacuum maintained in chamber 62, the pressuredifferential on opposite sides of diaphragm 42 effects translationthereof forcefully to the right carrying therewith power shaft 35-whichis joined to brake.operating Piston 33 to obtain power braking.

Hydraulic piston 33 hasa passage II therethrou h adapted to be closed byball valve "I2 retained within piston 33 by spring I3 and pin I4; Ballvalve operating member I5 adapted to unseat ball I2 and to permit itsseating relative to piston passage II, is adjustably retained withinmember I8 relativelyto shaft 35, the ends of pin 16 being held by coiledspring 18 provisioned between theend flanges of said sleeve. Ring 881sresilient action of spring acts as a stop limiting movement of ring 88to the right, and movements ofxsleeve 18 to the left.

pin 16 controls the 'master cylinder.

Operation on initial application of the vehicle foot pedal energizingmaster cylinder l5 and directing fluid under pressure through conduiti8, fluid enters the chamber between pistons 33 and 38 eflectingmovement to the left of valve piston 38 with some fluid passing throughpassage 'II in piston 3-3.

Ring 88 and sleeve I8 follow piston 38 to the left under action of ballspring I3, permitting movement to the left of pin 16 and valve member i5retained thereby. Ball .12 is thus permitted to close passage ll underexpansive action of spring 33. Movement of sleeve I8 to the. left -endswhen spring 33 becomes inoperative on ball I2 seating over opening II ad piston 33'; and a spaced relation now exists between said sleeve andpiston 33.

Movement of piston 38 to the left has operated the air and vacuumcontrol valve 2I--22 and power rod 35 is projected to th right throughpiston 38in the manner above described. Piston 33 with its passage IInow closed, operatively acts upon the brake fluid within cylinder 84directing the same at relatively high pressure to the vehicle brakewheel cylinders II throughport l3.

Movement of power rod 35 to the right also effects movement of sleeve 78which is loosely joined thereto by pin I6. However as rod 35 and piston33 move as a unit sleeve member I8 merely floats along therewith but aspaced relation is still maintained between said sleeve and piston 33.On brake release fluid pressure in the chamber between pistons 33 and 38is reduced practically to zero permitting return movement of valvepiston 38 to the right under action of spring 51 closing off the air tochamber 68 and again establishing vacuum communication thereto by returnpanied by a relative movement therethrough to' the left of power shaft35 under action of spring 41, and the relatively high fluid pressure inthe hydraulic chamber of cylinder ll. Return of piston 33 joined to rod351s limited by engagement of sleeve I8 with stop pin 8|. However it isto be noted that the pre-existing spaced relation between sleeve I8 andpiston 33 permits movement of piston 33 relative to said sleeve, and pinI6 now-retained by sleeve I8 prevents movement of ball unseating memberI5 with the result that ball I2- is promptly unseated permitting a quickrelease of the fluid under pressure in the tained inunediately uponrelease of the vehicle foot pedal operating pivotal member l6 whichValve operating piston 38 returnsto the right, piston 33 and rod 35return to-the left, and the ball valve I2 is simultaneously unseatedreleasing fluid pressure from the vehicle brake cylinders II.

It will benoted that annular ring 82 secured upon power ,rod 35.is'adapted to engage coil I spring 83 which is housed within theextended interposed between sleeve I8- and sealing cup 33 and ismaintained against thevlatter formove-v portion 48 of valve body member2|, thereby providing a yielding seat for said power shaft.

It will be noted however that spring 83 effects a slight translation tothe right of rod 35 and its piston 33, so that a spaced relation isagain established between sleeve. I8 and stop pin 8|. Thus it is seenthat on the next brake application sleeve I8 is free to move to the leftas above described in detail. r

fect of unseating ball valve 12 very prompt brake release. 3

a q It will also .be: noted that'the -inner;-'circuiar*ieftward:movement of piston it. Thus it is seen thatthepressuredifferential-on opposite sides of portion ofair valve seat3iis securedat a plurality ofgpoints' around valve bodymember 2| by I v v a I screws84. It further be .noted'that hollow wd' theextent'of this resistance isproportional power shaft" has a plug 85 at one end for clos- 5 to thejfe'xtent of the pressure differential. Con- 'ing oif theopening insaidshaftfromthe cham-:

ber between pistons 33 and 38.

As previouslydescribed return movement of piston 33 as well as means 3!,I! under action of spring .1, is limited by'engagement of-sleeve l8 withstop pin Ii. "However, it will.be seenthat large-spring lljisnow fullyexpanded, At'the same time smaller coil spring 83 hasv been fullymovement to-the right of shaft release return movement, J

In addition tothe force means 33-.4H2 it isclear that the brake re- 3!after its brake lease springs ll shown in Figure 1 are also effective incausingthe. return Iof said means.

. when the sleeve or, ring "I3 contacts the stop pin of" spring "41 upondetermining com'pressed'to 'fthe extentthat there is aismallg posedtherein providing a fluid chamber 'therebetween. there being a secondaryfluid chamberin' said cylinder for delivering fluidunder pressure, a I

8|, valve I2 will open, dissipating the, remaining returnforce'onpiston33 by brake return springs,

Ii. ,As above described spring was originally compressed under action ofboth the springs and II. With springs ll vno longer effective,

spring 83 will expand partially causing means 38-42-33 to' move slightlyv to theright. 1 It is this movement to the right .which establishesthe initial spaced relation between pin-ll and they sleeve 18. 1

It is'this slightmovement to the right of shaft which reestablishesaspaced relation between stop pin 3l and sleeve 13; Thisinitialspacedrelation-between members 3i and 131s necessary because itprovides a means of permitting seating.

of ball valve 12 prior to power movement of shaft '35, Consequentlyshaft is immediately effecdiaphragm?! tends to resist brake applicationsequently on brake'application a counter force is createdwhich tends toresist brake- ,application,

I gives to; the operator a certain pedal feel as the brakes'areappliediHaving described my invention,

and which should now be had to the claims which the scope thereof. 'Iclaimz 1.'- Thelcombinationya hydraulic cylinder, valve control andfluid control pistons. oppositely. dispressure engagement with said.valve'controlpis- 1 ton for effecting'movement thereof, "'a powerchambena movabie'member therein, means on said member slidably extendingthrough 7 said .valve control piston andjoined atits outer'rnd tosaid-fluid control piston and adapted to forceful translation upon apressure differential on oppotive, on actuating. piston 33 as ball valve12 hasv been seated over opening ll prior to movement of power shaft".,Thus any possible lag in brake application is eliminated.

On brake release means 33, 35, 42 ing to the left, andmeansll flrstcontacts stop ll. However, as above described there is still a spacedrelationbetwen means" and piston 33. .And it is thefurther movement ofpiston 33 ,to-

are returnsite. sides of said movable member, and air and vacuum controlvalve intermediate said cylinder and power chamber engageable by saidvalve .ccn-

-'trol .piston' for eflecting said differential,- and valve means insaid fluid control piston engaged by and responsive to initial movementsof said valve vcontrol piston for closing the. opening .therein. I 2.The combination, a hydraulic cylinder,- 8.

power chamber containing a movable-diaphragm therein deflninga vacuumchamber and an opcrating chamber on opposite sides'thereof, an airandvacuum control valve housing'intermediatc and co-axial with saidcylinder'and power chamher, a movable valve member therein, a die.-

phragm: peripherally secured within said housing and supporting saidvalve member, the latter' being adapted to alternately provide 'vacuumand wards the stoppedmeans II which has'the ef-.

It will be understood that ,with the brakes apand additional fluid willflow 'into the chamber for obtaining a- Y between pistons 38 and 33 .totakeup the increased volume of that chamber. because any'decrease in'the fluid pressure in said chamber between pistons 38 and 33is'automatically taken up by the reaction pressure or pedal feel of the..operator'in making the master cylinder pedal fully effective.

Referring to the operation of diaphragm means 68 initially, and beforebrake application a .bal-

anced vacuum condition exists on both sidesv thereof. However, as piston33 moves to the left vacuum is cut off to the chamber to the left ofThis follows air communication through said housing to said operatingchamber, a valve operating piston 7 adapted tooperatively engagesaid'movablevalve member, and a brake fluid controlpiston both in saidcylinder, providing a fluid chamber there-' between, there being asecondary fluid chamber.

in'said cylinder for delivering fluid under pressure, a manuallycontrolled pressure fluid source .connected to said cylinderintermediate said pistons adapted for communication through an openingin said fluid control piston and for'pressure engagement with/said valveoperating piston, a plunger rod slidably provisioned =throughsaidhousing, movable valve membenand valve piston,

joined at one end to said movable diaphragm and ,l

at its other end to said fluid control piston, and

' resiliently urged valve means in said fluid control piston engaged byand responsive to movements of said valve control piston for closing thetherein. a a

' 3. The combination, a power chamber having amovable member thereindefining an operating chamber and a vacuum chamber, a hydraulic cylindercontaining a brake fluid control piston opening and a valve controlpiston providing a fluid chamber therebetween, therebeing asecondaryfluid chamber in said cylinder for delivering fluid under pressure, amanually controlled pressure reference follow for:

fluid source connected to said cylinder intermediate said pistonsadapted for'communication,

through anopening in said fluid control piston and for operativepressure engagement with said valve control piston, a valvehousinghaving air and vacuum inlet ports, and an outlet port communicating withsaid operating chamber, a hollow reciprocable valve member in saidhousing, a diaphragm peripherally secured to sa d housing and centrallycarrying said movable member providing therebetween a normally closedair passage between said air port and said outlet port, said valvecontrol piston being normally spaced from said valve member providing anormally open vacuum passage between said vacuum port and said outletport, whereby progressive movement in one direction of said valvecontrol I power chamber movable member at one end and to said fluidcontrol piston at its other end, slidably provisioned through said valvehousing, said valve member, and through said valve operating piston, andresiliently urged means in said fluidcontrol piston responsive tomovement of said valve control piston for closing the openingtherethrough.

4. A power unit comprising a hydraulic cylinder containing fluid to besupplied under varying pressures to the wheel brake cylinders of avehicle, a piston in said cylinder operable on said fluid, a manuallyoperable pressure fluid source connected to said cylinder andcommunicating with said fluid through an opening in said piston, a powerchamber, a movable member therein joined at its outer end to said pistonand adapted to translation upon a pressure differential on oppositesides of said movable member, an air and vacuum control valve co-axialwithand intermediate said cylinder and power chamber for effecting saiddifierential, a secondary piston in said hydraulic cylinder in spacedrelation to said first piston engageable with said valve for controllingthe same and operable upon by said manually operable pressure fluidsource, valve means in saidflrst piston for closing the opening therein,and valve unseating means intermediate said valve means and saidsecondary piston, responsive to movements of 'said secondary piston.

5. The combination, a hydraulic cylinder, valve control and fluidcontrol pistons oppositely disposed therein providing a fluid chamberthere- I between, there being a secondary fluid chamber in said cylinderfor delivering fluid under pressure, a manually controlled pressurefluid source joining said first chamber, adapted for communication withsaid secondary chamber through an opening in said fluid control piston,and for operative pressure engagement with said valve control piston foreffecting movement thereof, a power chamber, a movable member therein,means 'on said member slidably extending through said valve controlpiston and joined at its outer end to said fluid control piston andadapted to forceful translation upon a pressure diflerential on oppositesides of said movable 8. chamber, and air and vacuum control valveintermediate said cylinder and power chamber. engageable by said valvecontrol piston for effecting said difierential, valve means in saidfluid control piston for closing the opening therein, and valveunseating means loosely carried within the means on said movable memberand intermediate said valvemeans and said secondary piston, responsivetomovements of said secondary piston and the means on said movable member.

-6. A power unit comprising a hydraulic cylinder containing fluid to besupplied under varying pressures to the wheel brake cylinders of a'vehicle, a piston in said cylinder operable on said fluid, a manuallyoperable pressure fluid source connected to said cylinder andcommunicating with said fluid through an opening in said piston, a powerchamber, a movable member therein joined at its outer end to said pistonand adapted to translation upon a pressure difierential'on oppositesides of said movable member, an air and vacuum control valve 'co-axialwithand intermediate said cylinder and power chamber for ef-,

means being so constructed as to effect closing ofsaid opening beforetranslation of said movable member. 1

7. 'I'he combination, a hydraullc cylinder, an air and vacuum valvecontrol piston and a brake fluid control piston in said cylinderproviding a fluid chamber therebetween, there being a secondary fluidchamber in said cylinder for delivering fluid under pressure, a manuallycontrolled pressure fluid source connected to said cylinder intermediatesaid pistons .adapted for communication through an opening in said fluidcontrol piston and for operative pressure engagement with said valvecontrol pistoma power chamber consisting of a pair of cooperating shellmembers having adjoining annularly flanged portions, a flexiblediaphragm with a peripheral rib annularly retained between said flangedportions, and an expansible U-shaped clamping ring enclosing saidflanged portions compressing the same for securing said diaphragm withinsaid chamber, a power shaft secured to said diaphragm slidably extendingthrough said valve control piston and joined at its outer end to saidfluid control piston and adapted to forceful translation upon a pressuredifferential on oppositesides of said diaphragm, an air and'vacuumcontrol valve intermediate said cylinder and power chamber engageable bysaid valve control piston for effecting said diflferential, andresiliently urged valve means in said fluid control piston responsive tomovements of said valve control piston for closing the openingtherethrough.

8. A power unit comprising a hydraulic cylinder containing fluid to besupplied under varying pressures to the wheel brake cylinders of avehicle,

a piston in said cylinder operable on said fluid, a

' cases 9 valve mechanism for said motor co-axial with said cylinder andpower chamber, movable means in said cylinder in spaced relation to saidpiston, a

I secondary piston engageable with said valve mechanism for actuatingthe same, responsive to said manual pressure source, said movable meansbeing responsive to movements of said secondary piston valve means insaid fluid control piston for closing the opening therethrough, saidvalve means, movable means, and said fluid control 1. piston beingconstructed to afl'ord communication through said piston when said motoris deenergized, and to close otl' communication therethrough before saidmotor is energized on application of said manual pressure source, andre- 1 2,359,687

silient means engageable with said motor to eflect onde-energization-thereoi' return of said fluid control piston to itsinoperative position.

, GORDON R. ELLIOTT.

REFERENCES CITED 1.

The following references are of record in the file of this patent:

UNITED STATES PATENTS

